This project focuses on studies relevant to a possible future rhinovirus (RV) vaccine. The fact and extent of possible antigenic shift in RV is being explored by continuing surveillance of RV serotypes active in Seattle, comparing recent and earlier isolates identified as the same serotype for possible antigenic differences and characterizing new "untypable" isolates with respect to possible relation to established RV serotypes. The possibility that concurrent dual RV infections may, by genetic recombination, provide a mechanism for antigenic shift is suggested by recent data indicating that 3.7% of 135 RV-positive specimens contained 2 RV serotypes. Hence, special efforts will be made to determine the true frequency and pattern of occurrence of dual RV infections. Finally, exploration of antigenic cross-relations between RV will be continued using an animal model for detection of responses of sensitized (primed host) to heterotypic "booster" stimuli. BIBLIOGRAPHIC REFERENCES: Fox, J.P.: Is a rhinovirus vaccine possible? Am. J. Epidemiol., 103, 1976. Fox, J.P, Cooney, M.K., Hall, C.E.: The Seattle Virus Watch. V. Epidemiologic observations of rhinovirus infections, 1965-1969, in families with young children. Am. J. Epidemiol., 101:122-143, 1975.